Relationship between the method of detection and prognostic factors for breast cancer in a community with a screening programme

Breast density, benign breast disease, and risk of breast cancer over time

OBJECTIVES

Assessing the combined effect of mammographic density and benign breast disease is of utmost importance to design personalized screening strategies.

METHODS

We analyzed individual-level data from 294,943 women aged 50-69 years with at least one mammographic screening participation in any of four areas of the Spanish Breast Cancer Screening Program from 1995 to 2015, and followed up until 2017. We used partly conditional Cox models to assess the association between benign breast disease, breast density, and the risk of breast cancer.

RESULTS

During a median follow-up of 8.0 years, 3697 (1.25%) women had a breast cancer diagnosis and 5941 (2.01%) had a benign breast disease. More than half of screened women had scattered fibroglandular density (55.0%). The risk of breast cancer independently increased with the presence of benign breast disease and with the increase in breast density (p for interaction = 0.84). Women with benign breast disease and extremely dense breasts had a threefold elevated risk of breast cancer compared with those with scattered fibroglandular density and without benign breast disease (hazard ratio [HR] = 3.07; 95%CI = 2.01-4.68). Heterogeneous density and benign breast disease was associated with nearly a 2.5 elevated risk (HR = 2.48; 95%CI = 1.66-3.70). Those with extremely dense breast without a benign breast disease had a 2.27 increased risk (95%CI = 2.07-2.49).

CONCLUSIONS

Women with benign breast disease had an elevated risk for over 15 years independently of their breast density category. Women with benign breast disease and dense breasts are at high risk for future breast cancer.

KEY POINTS

• Benign breast disease and breast density were independently associated with breast cancer. • Women with benign breast disease had an elevated risk for up to 15 years independently of their mammographic density category.

Bayesian joint ordinal and survival modeling for breast cancer risk assessment

We propose a joint model to analyze the structure and intensity of the association between longitudinal measurements of an ordinal marker and time to a relevant event. The longitudinal process is defined in terms of a proportional‐odds cumulative logit model. Time‐to‐event is modeled through a left‐truncated proportional‐hazards model, which incorporates information of the longitudinal marker as well as baseline covariates. Both longitudinal and survival processes are connected by means of a common vector of random effects.

General inferences are discussed under the Bayesian approach and include the posterior distribution of the probabilities associated to each longitudinal category and the assessment of the impact of the baseline covariates and the longitudinal marker on the hazard function. The flexibility provided by the joint model makes possible to dynamically estimate individual event‐free probabilities and predict future longitudinal marker values.

The model is applied to the assessment of breast cancer risk in women attending a population‐based screening program. The longitudinal ordinal marker is mammographic breast density measured with the Breast Imaging Reporting and Data System (BI‐RADS) scale in biennial screening exams. © 2016 The Authors. Statistics in Medicine Published by John Wiley & Sons Ltd.

The impact of preoperative axillary ultrasonography in T1 breast tumours

OBJECTIVES

To (a) determine the diagnostic validity of axillary ultrasound (AUS) in pT1 tumours and whether fine-needle aspiration (FNA) improves its diagnostic performance, and (b) determine the negative predictive value (NPV) of AUS in a simulation environment (cutoff: two lymph nodes with macrometastases) in patients fulfilling American College of Surgeons Oncology Group (ACOSOG) Z0011 criteria.

MATERIALS AND METHODS

This retrospective multicentre cross-sectional study analysed diagnostic accuracy in 355 pT1 breast cancers. All patients underwent AUS; visible nodes underwent FNA regardless of their AUS appearance. Sentinel node biopsy and axillary lymph node dissection (ALND) were gold standards. Data were analysed considering micrometastases 'positive' and considering micrometastases 'N negative'. The simulation environment included all patients fulfilling ACOSOG Z0011 criteria.

RESULTS

Axillary involvement: 22.8 %; AUS sensitivity: 46.9 % (Nmic positive)/66.7 % (Nmic negative); AUS+FNA sensitivity: 52.6 % (pNmic positive)/72.0 % (pNmic negative). In the simulation environment, AUS had 75.0 % sensitivity, 88.9 % specificity and 99.2 % NPV.

CONCLUSION

AUS has moderate sensitivity in T1 tumours. As ALND is unnecessary in micrometastases, considering micrometastases 'N negative' increases the practical impact of AUS. In patients fulfilling ACOSOG Z0011 criteria, AUS alone can predict cases unlikely to benefit from ALND.

KEY POINTS

• AUS+FNA can predict axillary involvement, thus avoiding SNB. • Not all patients with axillary involvement need ALND. • Axillary tumour load determines axillary management. • AUS could classify patients according to axillary load.

Clinicopathological differences between interval and screen-detected breast cancers diagnosed within a screening programme in Northern Portugal

Objective

To evaluate clinicopathological differences between screen-detected (SD) and interval (IC) breast cancers diagnosed in women enrolled in an organized breast screening programme in 2000--2007.

Setting

Breast Cancer Screening Programme of the north region of Portugal.

Methods

Using data from the screening programme and from the population-based North Region Cancer Registry, SD and IC were identified. Information on screening history, age, date of diagnosis, tumour size, histological type and grade, lymph node status, tumour stage, biomarkers, and treatment was obtained from the cancer registry and from clinical and pathological reports. Association between mode of detection and these clinicopathological characteristics was estimated by unconditional logistic regression.

Results

A total of 442 SD and 112 IC were identified in women aged 50--69. Compared with SD, IC were diagnosed in younger women (60.0 ± 5.8 years and 58.4 ± 6.0 years, respectively), were larger (tumour size >20 mm: 60.2% versus 25.1%), lobular (6.3% versus 16.1%), with a higher differentiation grade (grade 3: 17.7% versus 38.9%), had more lymph node metastases, more advanced stage, and oestrogen receptor (ER) negative (12.9% versus 29.0%) and progesterone negative, and HER2 positive. After multivariable analysis, compared with SD, IC were more likely to be larger than 20 mm, lobular, of grade 3 and negative for ER.

Conclusion

Our results are consistent with other studies. IC’s have a more aggressive biology than SDs. Our findings did not show any unexpected pattern requiring changes to our screening procedures, but continuous identification and characterization of IC is advisable.

An assessment of existing models for individualized breast cancer risk estimation in a screening program in Spain

Background

The aim of this study was to evaluate the calibration and discriminatory power of three predictive models of breast cancer risk.

Methods

We included 13,760 women who were first-time participants in the Sabadell-Cerdanyola Breast Cancer Screening Program, in Catalonia, Spain. Projections of risk were obtained at three and five years for invasive cancer using the Gail, Chen and Barlow models. Incidence and mortality data were obtained from the Catalan registries. The calibration and discrimination of the models were assessed using the Hosmer-Lemeshow C statistic, the area under the receiver operating characteristic curve (AUC) and the Harrell’s C statistic.

Results

The Gail and Chen models showed good calibration while the Barlow model overestimated the number of cases: the ratio between estimated and observed values at 5 years ranged from 0.86 to 1.55 for the first two models and from 1.82 to 3.44 for the Barlow model. The 5-year projection for the Chen and Barlow models had the highest discrimination, with an AUC around 0.58. The Harrell’s C statistic showed very similar values in the 5-year projection for each of the models. Although they passed the calibration test, the Gail and Chen models overestimated the number of cases in some breast density categories.

Conclusions

These models cannot be used as a measure of individual risk in early detection programs to customize screening strategies. The inclusion of longitudinal measures of breast density or other risk factors in joint models of survival and longitudinal data may be a step towards personalized early detection of BC.

Are prognostic factors more favorable for breast cancer detected by organized screening than by opportunistic screening or clinical diagnosis? A study in Loire-Atlantique (France)

PURPOSE

Comparisons of breast cancer characteristics between organized and opportunistic screening have been limited. This study was designed to compare characteristics of cancers detected by either organized or opportunistic screening as well as clinically diagnosed cancers in Loire-Atlantique (a French administrative entity), from 2003 to 2007.

METHODS

This study is based on data from the population-based Loire-Atlantique Cancer Registry. Stage at diagnosis and prognostic characteristics of carcinomas detected by organized screening were compared, by age-adjusted logistic regressions, to those of cancers detected by opportunistic screening and diagnosed clinically. Analyses were restricted to women aged 50-74 years (the age group targeted by the organized screening program) for the 2003-2007 period.

RESULTS

Between 2003 and 2007, 2864 invasive and 400 in situ breast cancer cases were diagnosed in women aged 50-74 years in Loire-Atlantique. Compared to cancers diagnosed clinically, cancers detected by organized screening were more likely to be in situ (13.7% vs. 3.8%), diagnosed at an early stage (74.4% vs. 51.3%), have a low SBR grade (grade 1: 35.4% vs. 18.5%), and be positive for estrogen-progesterone receptors (68.3% vs. 59.0%). The distribution of stage at diagnosis and prognostic characteristics between organized and opportunistic screening were similar.

CONCLUSION

These findings are consistent with the hypothesis that breast cancers are detected early by organized screening. Cancer characteristics were similar between the two screening modes. Estimating the impact of mammography screening on mortality in Loire-Atlantique should be the object of further investigations.

Asymptomatic Breast Cancer in Non-Participants of the National Screening Programme in Norway: A Confounding Factor in Evaluation?

Objective

To evaluate the extent and histopathological characteristics of asymptomatic breast cancer detected outside the Norwegian Breast Cancer Screening Program (NBCSP) in women targeted by the programme.

Methods

Our study included 568 primary breast cancers (523 invasive and 45 ductal carcinoma in situ) diagnosed in 553 women aged 50–70, residing in Møre og Romsdal County, 2002–2008. The cancers were divided into screening-detected cancers in the NBCSP, interval cancers (ICs) and cancers detected in women not participating in the NBCSP (never participated and lapsed attendees), and further into asymptomatic and symptomatic cancers. Nottingham Prognostic Index (NPI) was used for comparisons across the groups and the distributions were compared using chi-square tests for statistical significance.

Results

Twenty percent (19/97) of the ICs and 32% (69/213) of the breast cancers in non-participants were asymptomatic, with opportunistic screening as the most frequent detection method (42%, 8/19 for ICs and 54%, 37/69 for non-participants). There were no differences in distribution of NPI prognostic categories across subgroups of asymptomatic invasive cancers (screening-detected cancers in the NBCSP, asymptomatic ICs and asymptomatic cancers in non-participants) or between subgroups of symptomatic invasive cancers (symptomatic ICs and symptomatic cancers in non-participants). Asymptomatic cancers had a significantly more favourable distribution of NPI prognostic categories compared with symptomatic cancers ( P < 0.001). The proportion of invasive cancers with excellent/good NPI was 53% (164/310) for all asymptomatic and 25% (52/211) for all symptomatic invasive cancers.

Conclusions

A considerable percentage of breast cancers detected outside the organized screening programme were asymptomatic, with a prognostic profile comparable with screening-detected breast cancers in the NBCSP. Individual data regarding the detection method for all breast cancers are needed for a complete evaluation of the organized screening programme in Norway.

Interval breast cancers in a community screening programme: frequency, radiological classification and prognostic factors

The frequency of interval cancers (IC) can be an indicator inversely related to the quality of a breast screening programme. The objectives were to estimate the frequency of IC, to classify IC by posterior radiological review, and to describe the prognostic factors of these IC. The setting was the Sabadell-Cerdanyola Breast Cancer Screening Programme, in Northeast Spain. We developed a population-based study of the IC occurring in the first three rounds (1995-2001). The indicators used were the incidence rate of invasive IC per 10 000 women screened and the proportional incidence, stratified by age group, type of screening and the round, and the time elapsed since the last screening mammogram. A radiological informed consensus review was used to classify the IC. No specific pattern of incidence rates was evident with respect to age, type of screening, or round, although screening was generally more sensitive in women aged 60-69 years. The proportional incidence for the period 0-11 months was always under 30%. Twenty-one percent of 38 IC evaluated (95% CI: 8.0-34.0) were attributed to errors in the screening process (false negatives). No major differences in the prognostic factors of the 57 IC were identified on examining the radiological type or the time since the last screening mammogram. We observed a high frequency of IC from 12 months after screening. It is necessary to reach a consensus regarding the definition and the analysis of IC and to establish mechanisms that would allow all the malignant tumours diagnosed in the target population to be identified.